Electron beam deflection multivibrator circuits



Feb. 17, 1959 G. A. NEFF 2,874,283

ELECTRON BEAM DEFLECTION MULTIVIBRATOR CIRCUITS Filed July 30. 1954 2.5 242 l( Y IL INVENTOR. GLYN'ANE/f W,W&M

ATTORNEYS United States Patent C ELECTRON" nEFLE'cTmN MULTIVIBRATORQIR'CUITS I Glyn- A; Nelr, PasadengnJCalifassignortby mesne'assignments; to- Consolidated Electrodynamics Cor-pum tion, Pasadena", "Califa. corporation of California Application July"30, 1954*, Serial No. 446900" LCIaima cuss-a7 This inventiorrrelates to multivibrator: circuits, andmore particularly to an improved multivibrator. circuit includinga beam deflection typeel'ectron tube- Multivibratorcircuits, r such as theuEccles-Jordan multivibrator circuit, have been employed extensively" in :elec' tronic equipment as relaxationoscillators; switching;cir-- cuits, gating circuits, and the like; As is well knownga multivibrator circuit" has twoconditions of operationwhich are alternately assumed;

In some instances-the circuitry islarrangedxisoi that the" multivibrator is r bi-stable in' which case? one: condition of operation is maintained until the circuit is forciblycaused to assume its other;- condition'of ,operation. I In: other instances, the circuitry of a multivibrator isarrangedto he mono-stable, in which case the circuit -remains.win-a* stable condition-of operation until- -forcibly. caused to asthe circuit, returns to its stable condition. In addition, multivibrators. arersornetimes arranged to beiree-running, in which case-the two" conditions of: operation -are--alternately. assumed at arate whichis-dependent upon thc time constantsmf the circuit alone. Therefore,inaccordance with the above, the word rnultivibrator as used herein is intended tomean a circuit which 'isadapted to have two conditions of operationalternately. assumed, and which may. be either-'bi-stable, mono.-stable,,.0r=free run ning.

In contrast to conventional multivibrator circuits which normally employ, a pair. of electron"tubes,:- eachof-.whichhas a separate electron beam, the: multivibrator of. my present invention includes a beamdefle ction type'electron tube having a. single cathode, a-pair,of anodesand-means for deflectingan electron beamufrom thesingle cathode towardeither one of the anodes. I

In one embodiment a voltage is derived which is a function of the current flowing to at least one of theanodes, and the derived voltage is appliedto ,thedeflecting means whereby an electron bleam"from the cathode is deflected toward a first one-of-- the anodes in a first condition of' operation and deflected toward the other of the anodes in' another condition of -operation.

Abetter understanding'of-my invention may b'e'had upon a reading ofithefollowing detailed 'descriptiorr-when taken in'conjunction with the drawings, inwhich: 7

Fig: 1=is a schematic circuitdiagrarn ofi a bi-stable multivibrator;

Fig; 2 is a schematic. circuit diagram of= a mom-stable some another condition: of -.ope ration, and after; at predetermined interval depending upon the time constants of w 2,874,283 1C 1 Patenied- F b 1 condition of operation. where an electron beam from the cathode-Sis directed toward the right-hand anode 12,anda negative going triggering pulse is applied to the control electrodefi via a terminal 13, the electron beam flowing; to-the right-hand anode 12 will be momentarily decreased. This causes the potential at the right-hand anode 12 to rise due to the decrease in the voltage drop across the loadimpedance 14.

The rise in potential at the anode 12 of the electron tube 4iscoupled-to the left-hand deflector electrode-9 via a coupling capacitance 15 and a resistance 16. The increase in potential .at'the deflector electrode 9 attractsv the electron beam from the cathode 5 toward alert-hand anode 1 1.- This causes the potential at the left-hand anode 11 todrop due to the increased voltage drop across the load impedance 17.

The decrease inpotential'at the'left-hand anode 11 iscoupled. to the right-hand deflector electrode 10 via. a

coupling capacitance 13 and'a resistance 19.v The de crease intthe potential at the deflector electrode 10 tends to releasethe electron beam from beingattracted. toward the right-hand anode lZJ This-action is cumulative until substantially all of the electron beam from the cathode 5} is directed toward the left-hand anode 11 and the circuit achieves a stable condition of operation.

Inlike manner, assuming the electron beam from thecathode S'l'is directed toward the left-hand anode" 11, and

a negative going triggering pulse is applied to the control electrode 6 via the terminal 13, the electron beam is momentarily decreased, thereby. causing the potential at the left-hand anode 11' to rise. The rise in potential'is coupled toithe right-hand deflector electrode 10, thereby tend ing,to attract the electron beam toward :the right-hand anode 12. As increasing amounts of electrons flow to theanode 12, .the potential at the anode- 12 drops and'thedropi in potential, ,when coupled to the left-hand deflector electrode 9, tends to release the electron beam from being,

attracted toward the left-hand anodev 11; Again the action is' cumulative until the circuit achieves a stable condition of operation in which substantially all of the electron beam from the cathode '5 is directed towardthe right-hand anode 12'. Thus, thecircuitry of Fig. 11mm tions as a bi-stable multivibrator. In contrast to conventional' multivibrators, however, a single electron tube having a single electron beam is employed, which results. in a substantial increase in efiiciency since only one electron beam need be generated'. v

The interval required for the multivibratorof Fig. l to change from onestable condition of operation to another may be varied by suitable selection of the time constantsof the right-hand coupling circuit, including the coupi'ng capacitance 18 and-the voltage divider comprising the resistances 19 andltl along with a suitable selection of the time constants of the left-hand coupling circuit, including the coupling capacitance 1S and thevoltage divider comprising the resistances l6 and 23.

' Output signals from the bi-stable multivibrator ofFig. 1 may be derived from the circuit in the same manner as from a conventional multivibrator. For example, one way in which complementary waves'm'ayfbederived is by means of the terminals 21 andZZ' -Whi'chare' connected taps on the load impedances 14 and 17;

The electron tube employed in the mono-stable'circuit' of Fig. 2 is similar'to thatemployed in Fig; 1; Conse the electron beam to be attracted toward the left-hand anode 11 and away from the right-hand anode 12. The resultant decrease in potential at the left-hand anode 11, due to an increase voltage drop across the load impedance 26, is coupled to the right-hand deflector electrode 10 via a coupling capacitance 27. This tends to deflect the electron beam toward the left-hand anode 11. The action is cumulative until the circuit achieves a condition of operation in which substantially all of the electrons of the electron beam from the cathode flow to the lefthand anode 11.

As the charge on the coupling capacitance 27 leaks ofi, the right-hand deflector electrode tends to assume a potential determined by the voltage divider comprising a resistance 28 and a resistance 29. As this happens, the electron beam is deflected toward the right-hand anode 12 and away from the left-hand anode 11, and as an increasing amount of electrons flow to the right-hand anode 12, the resultant rise in potential at the left-hand anode 11 is coupled to the right-hand deflector electrode via the coupling capacitance 27, thereby tending to cause the electron beam to be further deflected toward the righthand anode 12.

Thus, the circuitry of Fig. 2 functions as a mono-stable multivibrator, which when forcibly caused to assume its unstable condition by applying a positive going pulse to the terminal 24, will remain in its unstable condition for a time interval dependent in part upon a suitable selection of the time constant of the coupling capacitance 27 and the voltage divider including the resistances 28 and 29.

The electron tube employed in the free-running multivibrator circuit of Fig. 3 may be the same type as that employed in Figs. 1 and 2 and, consequently, like reference characters have been used to designate the various elements.

Assuming that the free-running multivibrator of Fig. 3 has just assumed the condition of operation in which the electron beam from the cathode 5 is directed toward the right-hand anode 12, the drop in potential at the righthand anode 12, as a result of an increased voltage drop across the load impedance 31, is passed to the left-hand deflector electrode 9 via a capacitance 32. At the same time, an increase in potential at the left-hand anode 11, caused by a decrease in the current flowing through the load impedance 33, is passed to the right-hand deflector electrode 10 via a capacitance 34.

While the capacitance 32 and the capacitance 34 remain charged by the aforementioned changes in potential at the anodes 11 and 12, the electron beam from the cathode 5 will be deflected to the right-hand anode 12. However, as the capacitance 32 discharges through a resistance 35 and the capacitance 34 discharges through a resistance 36, the electron beam tends to swing toward the center, and the current flowing to the left-hand anode 11 increases while the current flowing to the right-hand anode 12 decreases. The resultant drop in potential at the left-hand anode 11 is coupled to the deflector electrode 10 via the capacitance 34, and the resultant rise in potential at the right-hand anode 12 is coupled to the left hand deflector electrode via the capacitance 32. This action is cumulative until substantially all of the electron beam is deflected to the left-hand anode 11.

Again, as the capacitance '32 and the capacitance 34 discharge via the resistances 35 and 36, the electron beam tends to swing toward the center, thereby causing a rise in the potential at the left-hand anode 11 and a drop in the potential at the right-hand anode 12. As previously noted, this causes a cumulative action which tends to defleet the electron beam further toward the right-hand anode 12. This action, in which the electron beam is deflected back and forth between the left-hand anode 11 and the right-hand anode 12, takes place at a rate dependent primarily upon the time constants of the lefthand coupling circuit including the capacitance 32 and the resistance 35, and the right hand coupling circuit including the capacitance 34 and the resistance 36. Thus, the circuit of Fig. 3 functions as a free-running multivibrator.

Output signals from the circuit of Fig. 3 may be derived in a manner similar to that employed in a conventional multivibrator circuit. In addition, the free-running multivibrator of Fig. 3 may be synchronized by applying a synchronizing signal as shown in Fig. 1 or 2, or in any manner in which a conventional free-running multivibrator may be synchronized.

By interconnecting a plurality of the bi-stable circuits of Fig. l, a counter may be formed which is capable of counting in binary notation. By inhibiting the operation of certain ones of the bi-stable multivibrators when certain registrations appear in the circuit as a whole, the circuit may be adapted to count in a permuted binary notation, e. g., from zero to nine. One circuit for inhibiting the passage of count pulses from one bi-stable multivibrator to another hi-stable multivibrator is shown in the co-pending United States patent application, filed May 12, 1954, Serial No. 429,353, in the names of Robert M. Strassner and Everett G. Shover, and entitled Signal Transfer Circuits.

One type of electron tube which may be used in each of the circuits of Figs. 1, 2 and 3 is the type 6AR8 sheet-beam deflector tube, which was originally developed for use as a color television synchronous detector. In some applications it may be possible to omit one or more of the electrodes 6, 7 and 8.

I claim:

A bi-stable circuit having two conditions of operation, including in combination an electron tube having at least a cathode, a pair of deflector electrodes, and a pair of anodes; a first impedance connected between a first one of the pair of anodes and the cathode; a second impedance connected between another one of the pair of anodes and the cathode; means cross-coupling the anodes and the deflector electrodes comprising a first resistance and a first capacitance connected in parallel between a first one of the pair of anodes and a first one of the pair of deflector electrodes and a second resistance and a second capacitance connected in parallel between the other one of the pair of anodes and the other one of the pair of deflector electrodes; and triggering means coupled to the electron tube for momentarily decreasing the electron flow from the cathode.

Australia Mar. 6, 1952 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,874,283 February 1'7, 1959 Glyn A. Neff It is herebfir certifiedv that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 62; after "connected" insert to center Signed and sealed this 9th day of June 1959.

(SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Attesting Oflicer Commissioner of Patents 

